The roof of a burning one-story warehouse collapsed just minutes after firefighters were ordered to get off and evacuated the building in Kansas City’s northeast area.

Fire crews have taken a defensive mode in fighting the two-alarm fire, which was reported before 6 a.m. at the building at East Ninth Street and Van Brunt Boulevard, said Battalion Chief Lew Hendricks, a Kansas City fire department spokesman.

The first crews, who are stationed nearby at Independence Avenue and Van Brunt, arrived less than a minute after being dispatched, Hendricks said.

They initially reported that there was little fire on the exterior of the building but they could see fire inside. As they entered to fight the blaze, other firefighters gained access to the roof and discovered a large amount of fire on the roof, Hendricks said.

As a precaution, the incident commander ordered everyone out of the building and off the roof. Because the building is vacant, officials decided to fight the fire in a defensive mode.

Within four minutes of the evacuation, the roof collapsed, Hendricks said.

Firefighters were using four aerial ladders to stream water onto the fire.

“They will be doing that quite a while before we gain entry again to put out the hot spots,” Hendricks said this morning. “We will have fire crews here for several more hours.”

The fire caused significant damage to the building. Kansas City’s dangerous buildings department has been notified.

The warehouse is in an area that is undergoing a significant amount of urban renewal.